package org.opentrafficsim.road.gtu.lane.perception.categories;
   
   import java.util.function.Supplier;
   
   import org.djunits.value.vdouble.scalar.Length;
   import org.djunits.value.vdouble.scalar.LinearDensity;
   import org.opentrafficsim.core.gtu.GTU;
   import org.opentrafficsim.road.gtu.lane.perception.PerceptionCollectable.Intermediate;
   import org.opentrafficsim.road.gtu.lane.perception.PerceptionCollectable.PerceptionAccumulator;
  import org.opentrafficsim.road.gtu.lane.perception.PerceptionCollectable.PerceptionCollector;
  import org.opentrafficsim.road.gtu.lane.perception.PerceptionCollectable.PerceptionFinalizer;
  import org.opentrafficsim.road.gtu.lane.perception.categories.AnticipationDensity.CountAndDistance;
  
  /**
   * Collector to determine density based on GTUs.
   * <p>
   * Copyright (c) 2013-2019 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="http://opentrafficsim.org/node/13">OpenTrafficSim License</a>.
   * <p>
   * @version $Revision$, $LastChangedDate$, by $Author$, initial version 13 mrt. 2018 <br>
   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
   * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
   */
  public class AnticipationDensity implements PerceptionCollector<LinearDensity, GTU, CountAndDistance>
  {
  
      /** {@inheritDoc} */
      @Override
      public Supplier<CountAndDistance> getIdentity()
      {
          return new Supplier<CountAndDistance>()
          {
              /** {@inheritDoc} */
              @Override
              public CountAndDistance get()
              {
                  return new CountAndDistance();
              }
          };
      }
  
      /** {@inheritDoc} */
      @Override
      public PerceptionAccumulator<GTU, CountAndDistance> getAccumulator()
      {
          return new PerceptionAccumulator<GTU, CountAndDistance>()
          {
              /** {@inheritDoc} */
              @Override
              public Intermediate<CountAndDistance> accumulate(final Intermediate<CountAndDistance> intermediate,
                      final GTU object, final Length distance)
              {
                  intermediate.getObject().increaseCount();
                  intermediate.getObject().setDistance(distance);
                  return intermediate;
              }
          };
      }
  
      /** {@inheritDoc} */
      @Override
      public PerceptionFinalizer<LinearDensity, CountAndDistance> getFinalizer()
      {
          return new PerceptionFinalizer<LinearDensity, CountAndDistance>()
          {
              /** {@inheritDoc} */
              @Override
              public LinearDensity collect(final CountAndDistance intermediate)
              {
                  return LinearDensity.createSI(intermediate.getDistance().si / intermediate.getCount());
              }
          };
      }
  
      /**
       * Intermediate data to determine density.
       * <p>
       * Copyright (c) 2013-2019 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved.
       * <br>
       * BSD-style license. See <a href="http://opentrafficsim.org/node/13">OpenTrafficSim License</a>.
       * <p>
       * @version $Revision$, $LastChangedDate$, by $Author$, initial version 13 mrt. 2018 <br>
       * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
       * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
       * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
       */
      public static class CountAndDistance
      {
  
          /** Count. */
          private int count;
  
          /** Distance. */
          private Length distance;
  
          /**
           * @return count.
           */
         public int getCount()
         {
             return this.count;
         }
 
         /**
          * Increases the GTU count by 1.
          */
         public void increaseCount()
         {
             this.count++;
         }
 
         /**
          * @return distance.
          */
         public Length getDistance()
         {
             return this.distance;
         }
 
         /**
          * @param distance Length; set distance.
          */
         public void setDistance(final Length distance)
         {
             this.distance = distance;
         }
     }
 
 }